1. Field of the Invention
The field of this invention relates to pipes and more particularly to a coupling for two pipe sections which are to be connected together in a fluid tight manner without requiring welding, soldering or other conventional types of permanent securing techniques.
2. Description of the Related Art
Plastic pipe has long been used for the conveying of fluid, such as liquids and gases. Any plastic pipe system will inherently include a series of connectors with these connectors being utilized to connect together aligned pipe sections of the overall pipe system. It is intended that these connectors must provide a fluid tight seal over a range of temperatures, pressures and a variety of exterior ambient conditions. Specifically for plastic pipe, a reliable connector is indeed rare owing to the stress to which the connectors are subjected due to environmental changes, pressure changes and temperature changes. These changes cause fatigue in the connectors which inherently result in leakage of gas or liquid from the connector.
One prior art of pipe coupling that is currently available is defined as a compression system. This type of coupling is large in size when compared to the plastic pipe which makes it difficult to install in limited space areas. Additionally, tools are needed to make the installation required for this compression system. Also, an extensive installation area is required to the large size of the compression system coupling making it virtually impossible to install such compression system couplings within restricted space areas like concrete walls.
Additionally, in the past, prior art pipe couplings were easily removed which led to the plundering of the fluid that is being conducted through the pipe sections. It would be desirable to design a pipe coupling that required special tools in order to remove the coupling thereby minimizing the possibility of unauthorized removal of any gas or liquid being conducted through the pipe system.
In the past, there have been manufactured pipe couplings where a pipe section is inserted into a connector and then moved in a withdrawing manner so that biting members dig into and grip the wall surface of the pipe section which results in the pipe section not detaching from the connector with a fluid tight connection being established between the connector and the pipe section. Within the prior art, it is common to construct the biting members of a hard plastic material. However, the hard plastic biting members are commonly ineffective when used in conjunction with solid PVC pipe or metallic pipe. Also, over time, the quality of the grip of the connector on the pipe section will deteriorate due to the fluctuation of the temperature of the fluids being conducted through the pipe section. In the past, if the biting members are constructed to be metallic, such have to be of substantial thickness in order to work satisfactorily. This increased thickness of the biting members causes inconvenience in the radial compression while at the same time a substantial amount of force is required to compress the grab ring that supports the biting members in order to penetrate the surface of the pipe section. Hence, these prior art difficulties frequently cause fatigue and deformation of the plastic exerting the compressive force.
One of the primary objectives of the present invention is to construct a plastic pipe coupling that is used for joining pipe sections in a liquid tight manner over a range of different pressures and temperatures.
Another objective of the present invention is to construct a plastic pipe coupling that can be easily installed without requiring any tools or special skills by the installer.
Another objective of the present invention is to construct a plastic pipe coupling that is compact in size making it easy to install in areas of limited space, such as when the pipe system is imbedded within a wall.
Another objective of the present invention is to construct a plastic pipe coupling that can be manufactured at a lower cost than other configurations of pipe coupling and therefore to be able to be sold to the ultimate consumer at a relatively inexpensive price.
The basic embodiment of the present invention is directed to a push-pull pipe coupling adapted for connecting a pair of pipe sections. A hollow connector has an internal chamber within which is adapted to be located a pipe section. Surrounding the pipe section is a coupler with this coupler including a grab ring housing which is annular in configuration and is located about the pipe section. The grab ring housing has an interior surface that is formed into an annular concavity. The coupler includes a grab ring mounted within this concavity with the grab ring having an annular wall which has a plurality of inwardly extending biting members. These biting members are adapted to abut against the pipe section. The biting members permit the pipe section to be moved relative to the connector in an installing direction, and when completely installed and a withdrawing movement applied to the pipe section, the biting members are caused to pivot and dig into the pipe section forming a solid securement between the connector and the pipe section.
A further embodiment of the present invention is where the basic embodiment is modified by the grab ring being defined as a split ring.
A further embodiment of the present invention is where the basic embodiment is modified by the annular concavity being defined as having a forward wall which is located at an acute angle which is less than the acute angle of the biting members prior to the withdrawing movement of the pipe section.
A further embodiment of the present invention is where the basic embodiment is modified by the annular concavity having a rear wall.
A further embodiment of the present invention is where the basic embodiment is modified by the grab ring housing being constructed of a hard plastic material.
A further embodiment of the present invention is where the basic embodiment is modified by the grab ring being constructed of a metallic material.
A further embodiment of the present invention is where the basic embodiment is modified by the grab ring housing having an annular front beveled surface.
A further embodiment of the present invention is where the just previous embodiment is modified by there being formed a second annular beveled surface on a retaining cap with the annular beveled surface of the grab ring housing to be in sliding contact with the annular beveled surface of the retaining cap.
A further embodiment of the present invention is where the just previous basic embodiment is modified by a washer having an annular beveled surface which is in engagement with the annular beveled surface on the grab ring housing.